With conventional types of hydraulic valve lifters, each valve actuating push rod seats in a plunger axially slidable in a lifter body, and the lifter body rides on one lobe of the cam. Oil from the engine lubrication system is introduced under pressure between the body and plunger, keeping the valve train at zero valve lash. Many lifters are designed to trap oil in the body chamber and pump up beyond its predetermined zero valve lash point, holding the valve open at high speeds causing valve float. However, with high preformance cams the valves are timed to have considerable overlap in order to provide for a large flow through the engine. At low speeds this large overlap is not necessary and the engine runs inefficiently, resulting in a loss in low speed horespower. Basically, increasing the valve lash will shorten valve open duration and reduce overlap, giving crankshaft rotating degrees in relationship to the opening of the valves. This will result in an improvement in low speed performance. However, excessive lash causes considerable noise and wear at idling and low speeds. The novel two-way valve varies valve timing automatically, by increasing or widening valve lash at low speeds improving low end torque horsepower, yet while the engine speed increases, the two-way valve allows the lifter to pump up, decreasing valve lash, consequently lengthing valve duration and overlap improving high speed performance.
The two-way valve described herein is designed to provide favorable characteristics over the other two patents. Herewith being much more precision, adjustable and readjustable for other cam profiles varing spring tension and oil weights, drop-in installation, also low cost manufacturing. A unique novel feature is that the two-way valve will in fact convert your own hydraulic lifter by the removal of the one way valve, and merely replacing it with the two-way valve converting your own lifters in a simple drop-in installation to a variable lifter, changing valve timing characteristics, improving engine performance, economy and smog pollutant emission factors.